This invention relates to mine roof bolting, and more particularly to anchoring means adapted to be secured within a bore in the roof by resin adhesive material, and to a method of utilizing the anchoring means to support the mine roof.
This invention involves an improvement over the prior art resin-secured anchoring means for supporting the roof of a mine, said prior art anchoring means generally involving a headless rod having screw threads toward one end and a nut threaded on the rod at that end or, alternatively, a rod having an integral head at one end thereof. The invention also involves an improvement in the prior art method of installing anchoring means in the roof of a mine, said prior art method involving drilling a bore in the roof, inserting unmixed resin therein, partially inserting the rod into the bore, mixing the resin by rotating the rod either by rotating the nut until it engages the unthreaded portion of the rod or rotating the integral head fully inserting the rod into the bore by forcing the rod up until the nut or head is in a pressing relationship with the roof, and continuing the application of the pressing force until the resin has hardened thereby securing the rod to the roof. The prior art anchoring means and the method of utilizing it provide "fully grouted" bolting satisfactory for the bonding or pegging of the roof strata together, but they do not provide "point anchored" bolting for the clamping of the roof strata together by tension developed in the anchoring means. "Point anchored" bolting is preferred over "fully grouted" bolting for certain types of roof strata.